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The corrosion potential and rate of depended on the feed direction and number of pass. 1.
As shown in Fig. 4-(b), route-A produces grains with high angle grain boundary.
The micro-hardness increases from 75 Hv to 190-210 Hv with increasing number of pass.
Deformation bands were more clearly observed as number of feeding increases.
Route-A produced grains with high angle grain boundary.

Table 1: Constants for copper grains ([27]).
It is seen in Fig. 3 that the nonhomogeneous part for the coarse grain size is small but when the grain size approaches to nonometer ranges, this part becomes dominant.
However, for simplicity, the strain gradient are computed here based on the directional derivative as: Dnf = ▽f.n (15) where n is the unit direction between the points and ▽f is: ▽ f = ∂f ∂xi + ∂f ∂y j (16) In Eq. 15, for the N number of nearest points around the interest point i, strain gradients are calculated.
It is demonstrated that for micro size grains, this effect is too low.
However, for 49 nm grain size, the difference is noticeable.

A wide variety of grain sizes and grain boundary distributions can be obtained by DRX directly during plastic working.
The new DRX grains appear only near initial grain boundaries.
New fine grains comprise a necklace structure forming at serrated initial grain boundaries; core areas of initial grains remain unrecrystallized.
However, new fine grains scarcely developed at serrated grain boundaries.
The numbers in schematic drawing indicate the boundary misorientations in degrees.

In addition, Ta element has effect on grain refinement and the number of γ′-Co3(Al,W) phase refines grain.
Cobalt, Tungsten, Aluminum, Tantalum powders purity and grain size are 99.95%, 99.96%, 99.5%, 99.9%, -300, -200, -325 and -200 meshes, respectively.
The 9.8W alloy grain is strips, but the grains of 2Ta alloy is ball rod along, and a large number of white particles at grain boundary precipitation on the matrix, the precipitation is γ'-Co3(Al,W) phase or A3B-type phase, which cannot be determined.
(2) Addition of alloying elements Ta can increase the number of γ' phase and refine grains of Co-8.8Al-9.8W superalloy, the high temperature properties of Co-Al-W superalloy is improved

An Atomistic View of Grain Boundary Diffusion MISHIN, Yuri1,a Department of Physics and Astronomy, MSN 3F3, George Mason University, Fairfax, Virginia 22030, USA aymishin@gmu.edu Keywords: Grain boundary, diffusion, modeling, simulations, molecular dynamics, correlations, liquid.
Introduction It has long been known that atoms diffuse in grain boundaries (GBs) orders of magnitude faster than in the crystalline grains, an effect which is often referred to as "short-circuit diffusion" [1].
(a) Probability distribution of the number of atoms in a cluster.
(b) Example of a log-log plot of the number of atoms in a cluster versus its gyration radius Rg.
Gust, Fundamentals of Grain and Interphase Boundary Diffusion (Wiley, Chichester, West Sussex, 1995)

At this time, a large number of quasi-solid-state atomic group had a good wetting function with nucleus, and the atomic group could develop into floating crystal quickly.
But in the process of solidification, latent heat still existed, so the grains could not grow the same way that equiaxed grains did , instead , they grew in a way between equiaxed grains and dendrite did, and finally the grains grew into rose-like shape.
The actual solidification process was a complex process of physical chemistry controlled by numbers of factors.
Even in a strong mixture convection, the melt was not a uniform and balance system, so grains might be in the shape of irregular or branchlike, and stirring may make grain collide and sinter, and then the grains could integrate into a big grain.
When the melt temperature drops to the liquidus level, the whole melt enters the state of undercooling immediately, and a large number of nucleation is formed

Ø Modeling of chip formation Ø Modeling of chip formation force for individual grain Ø Modeling of ploughing force for individual grain Ø Modeling of Grinding force Modeling of chip formation The total grinding force can be deduced from the total number of active grains multiplied by the average grain force.
The static number of cutting edges depends on the grain size, wheel porosity and dressing condition.The static cutting edge density function is depicted as following[3].
When the cutting depth of grain t is available, the diameter of the equivalent grain can be determined from the geometry as follows
The equivalent grain diameter depends on the shape of the grain and depth of cut of the grain[3].
(31) Here is the number of active cutting edge, and are the normal and tangential forces on a single grain.

Original grain distribution, grain size is 119μm 2μm 2μm Fig.1.
If a R-grain impinges upon another, both grains stop growing at the point of impingement.
(3) The nucleation of DRX will occur on grain boundaries (including primary grain boundaries and R-grain boundaries) or some other high-energy defects inside grains[7,8] 1.3 Recovery model.
There are a certain number of cells, N, which is chosen randomly from all the cells.
The number N is decided by the formula below: (3) Where M is total cells in CA model, K is a constant with 6030, is the increasing rate of dislocation density, and m is the sensitivity of stain rate.

In addition, recovery influences precipitation through its effect on the number of potential precipitate nucleation sites (i.e. number of dislocations).
An indirect effect of precipitation is to deplete Nb form solid solution leading to a reduction in the solute drag the Nb exerts on the grain-boundaries of the recrystallizing grains.
The number of dislocation nodes, nc, was approximated as 0.5ρ1.5.
A number of authors have shown that the Zener approach, or a modified version of it, accurately captures the effect of a stable particle distribution on the growth of the recrystallizing grains [12, 16-18].
Accelerated coarsening of the particles located at the grain boundary will lead to a local reduction in the pinning force and the boundary is able to advance (locally) until it encounters a sufficient number of fresh particles which will ensure that the boundary is pinned again.

In some cases, this network consists of a glassy phase present as thin grain boundary films merging into pockets at multi-grain junctions.
Secondary samarium melilite (Sm2Si3-xAlxO3+xN4-x) had formed in a number of the intergranular pockets (arrowed).
Imaging and chemical analysis Grain size and shape.
Oxynitride glass network modifiers also promote grain growth.
A grain growth exponent of 3 was determined, which indicates diffusion controlled grain growth [11].